1. Field of the Invention
The present invention relates to a laser microscope and a color laser microscope which uses a rectilinear light beam generating device for converting laser light into an incoherent rectilinear light beam.
2. Description of the Background Art
There has been used a laser microscope in which a surface of a sample to be observed is two-dimensionally scanned by a laser beam, and light reflected from the sample is received by a linear image sensor. In this laser microscope, a laser beam emitted from a laser source is deflected at a high speed in a main-scanning direction by an acoustic optical element and also deflected in a sub-scanning direction by a galvanomirror so as to two-dimensionally scan a surface of a sample. Since this laser microscope achieves high resolution by using a confocal optical system, it has been used widely for the use which requires a high-resolution image. Also, since a surface of a sample is two-dimensionally scanned by a laser beam in this laser microscope, there is an advantage that the quality of the image is not deteriorated even in a case where there is a speckle pattern in a laser beam.
The above-mentioned laser microscope which scans a surface of a sample with a laser beam has an advantage that it is possible to take a high-resolution image. However, it has a drawback of a high manufacturing cost because an acoustic optical element for deflecting a laser beam at a high speed in a main-scanning direction is expensive. Also, it has another drawback that it requires a large-scale structure because the sway angle of an acoustic optical element is relatively small and the optical path of the optical system needs to be adjusted to be long in order to obtain a required scanning length on a surface of a sample.
Also, since an acoustic optical element has wavelength dependence, it is necessary to prepare an acoustic optical element having a different adjustment condition for each color beam in the case of being applied to a color laser microscope. Consequently, the manufacturing cost becomes higher.
In addition, in a case where beam scanning is performed by using an acoustic optical element, it is necessary to precisely control the incident angle of the laser beam with respect to the acoustic optical element. Consequently, the adjustment of the optical system becomes complicated, and the design of the optical system of the whole microscope becomes complicated.
As a method for solving the above-mentioned problems, there is known a method in which a laser beam emitted from a laser source is converted into a rectilinear beam expanded in a single direction with a cylindrical lens, and a surface of a sample is scanned with the rectilinear beam. However, since a laser beam has high coherence, glare easily occurs and a speckle pattern is generated in the rectilinear light beam, which causes the quality of the image to be deteriorated. In this instance, it is assumed that a mercury lamp can be used as a light source. However, since a mercury lamp is large, the microscope apparatus is forced to be large.
An object of the present invention is to achieve a laser microscope in which a surface of a sample can be scanned two-dimensionally without using an expensive acoustic optical element.
Another object of the present invention is to achieve a laser microscope in which the design and adjustment of the optical system is simple, and the structure is small-scale.
Another object of the present invention is to achieve a color laser microscope in which a color image of a sample can be taken without using an acoustic optical element.